The present invention is with respect to an apparatus for separating suspended materials, such as ash or the like, from stack gases, made up of a cyclone-like coarse separator, a container for materials taken out of suspension from the gas, a fines separator on the outlet side and an outlet stack for the cleaned stack gas.
Such apparatus is more specially needed in connection with industrial combustion systems fired by solid fuel with the purpose of cleaning the stack gas to such a degree that amounts of noxious materials emitted into the outside air do not go up past limits fixed by public authorities.
The separate parts of the system--that is to say the coarse separator, the take-up container for the suspended material, the fines separator and the stack--are joined up by ducting, through which the stack gas makes its way at an above-atmospheric pressure. In such well known systems, more specifically in the separators and the ducting, there is a danger of sooting up (i.e., the deposition of soot from the dirty stack gas), especially upon shutting down the combustion system, when in fact the temperature in the system goes down under the dew point. For this reason, steps have to be taken for stopping sooting up and fouling, such as, more specifically, thermally insulating the parts of the system where trouble is likely, such as the separators and the ducting so that the heat coming from the stack gas, taken up by these parts, is stored, at least for a short time. Such measures naturally make the system more complex.